The US has been following the same path that both Greece and Portugal went down before their downgrades. As the deadline for the budget agreement comes closer so does the possibility of a government shutdown.

The US is going down a similar road as that taken by Greece and Portugal with regard to its budget decisions, John E. Silvia, chief economist at Wells Fargo, said on Wednesday.

"To me—being in Europe for a few days—the plot in Greece and Portugal sounds an awful lot like the same plot that's going on in the United States. But the characters have different names," he said.

As the deadline for a budget agreement looms in Congress, Silvia told CNBC that the US must recognize that the moderate economic growth forecast by most economists for the country will fail to generate the tax revenue necessary to fund long-running government entitlement spending.

"We have to make some arrangements in terms of cutting back the promises that were made by prior politicians for these entitlements," Silvia said.

"(We've had) forty years of political promises to give people certain entitlements, certain benefits. And we've now come to understand that the United States is in a very difficult position than it was in the early post-World War II period. We're not the dominant economy. And our pace of growth has moderated. Our ability to finance this is all limited."

Republicans and Democrats are at loggerheads over how to fund the federal government for the final six months of the 2011 fiscal year.

"It basically comes down to: Can the Democrats give a little bit in terms of spending over a longer-term time period?" said Silvia, who previously was a senior economist for the US Senate Joint Economic Committee.